JP2014086745A - Crystal oscillator with thermostat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal oscillator with a thermostat capable of improving thermal conductivity of a substrate, reducing thermal resistance among a heat source component, a crystal resonator and a temperature sensor, stabilizing the temperature and stabilizing an output frequency.SOLUTION: In a crystal oscillator with a thermostat, a crystal resonator, a heat source component which becomes a heat source, and a temperature sensor are packaged on a substrate. The substrate includes a copper plate 10 in a central portion (core portion) in a thickness direction, and prepreg layers 11, 12 each formed from a glass epoxy resin and copper foils 13, 14 are successively laminated on front and rear sides of a principal surface of the copper plate 10. The crystal oscillator with the thermostat may comprise an aluminum plate or a heat-conductive ceramic plate in place of the copper plate 10.

Description

  The present invention relates to a quartz crystal oscillator with a thermostat, and in particular, a quartz crystal with a thermostat capable of stabilizing the temperature by reducing the thermal resistance between the heat source component, the temperature sensor, and the crystal resonator, and stabilizing the output frequency. It relates to an oscillator.

[Description of Prior Art]
The Oven Controlled Crystal Oscillator (OCXO) is installed in a thermostatic chamber to shut off the outside air temperature, and the temperature of the crystal resonator is controlled by a temperature control circuit equipped with heat source components and temperature sensors. Keep it constant.
Thereby, OCXO suppresses the fluctuation | variation with the temperature of an output frequency, and can obtain the stable output frequency.

A general OCXO configuration will be briefly described.
In OCXO, for example, circuit components such as a crystal resonator, a temperature sensor, and a heat source component are mounted on a substrate, the substrate is fixed with a pin on a metal base, and a cover that covers the entire substrate is mounted on the base. The interior is sealed with a metal base and a cover.

  In OCXO, thermal coupling between the heat source component, the temperature sensor, the crystal unit and other circuit components (hereinafter simply referred to as “crystal unit”) is improved to eliminate temperature unevenness and stabilize temperature control. is important.

  In the conventional crystal oscillator with a thermostat, a glass epoxy resin (FR-4) substrate having a low thermal conductivity is used as the substrate, and the thermal resistance between the heat source component, the temperature sensor, and the crystal resonator is low. It gets bigger.

[Conventional substrate: Fig. 4]
A layer structure of a conventional substrate will be described with reference to FIG. FIG. 4 is a cross-sectional explanatory view showing a cross section of a substrate of a conventional thermostatic oven-equipped crystal oscillator.
FIG. 4 shows a four-layer substrate using a conventional glass epoxy resin. The central through hole is a through hole.
As shown in FIG. 4, the conventional substrate includes a core 30 made of glass epoxy resin (glass epoxy) at the central portion of the thickness, and inner layer copper foils 31 and 32 are provided on both upper and lower sides of the core 30. Furthermore, prepregs (prepreg layers) 33 and 34 made of glass epoxy are provided, outer layer copper foils 35 and 36 are formed on the outer sides thereof, and copper platings 37 and 38 are applied to the outermost layers.

That is, in the conventional substrate, the core material provided in the central portion in the thickness direction is a glass epoxy substrate such as FR-4, and the thermal conductivity is about 0.3 W / m · K, which is not so high.
For this reason, in a crystal oscillator with a thermostat using a conventional substrate, heat is transmitted slowly between the heat source component, the crystal resonator, and the temperature sensor, temperature unevenness occurs in the thermostat, and the oscillation frequency is low. It becomes stable.

  For example, when the ambient temperature of a crystal oscillator with a thermostatic chamber fluctuates, temperature unevenness occurs and the temperature is constant near the temperature sensor, but at a distance away from the desired temperature, causing a frequency change. It was.

[Related technologies]
In addition, as a technique regarding the structure of the substrate, JP 06-120629 A (Nippon Denso Co., Ltd., Patent Document 1), JP 08-288604 A (Electrochemical Industry Co., Ltd., Patent Document 2), JP 2012 No. -38769 (JTEKT Corporation, Patent Document 3).

In Patent Document 1, a metal-based multilayer wiring board has a through-hole formed in a portion where a power transistor is disposed, and a copper thin film is arranged in multiple layers so that the power transistor is mounted without spotting. The structure to be described is described.
Patent Document 2 describes a configuration in which two or more metal layers of a circuit board are laminated via an insulating adhesive in a metal-based multilayer circuit board.
Patent Document 3 describes a configuration in which components such as a power transistor and a temperature sensor are mounted on a copper laminated substrate in a switching drive circuit.

JP-A-06-120629 JP 08-288604 A JP 2012-38769 A

  However, in the conventional crystal oscillator with a thermostat, the thermal conductivity of the substrate is not good, so the thermal resistance between the heat source component, the crystal unit, and the temperature sensor is large, which hinders stable temperature control, and the output frequency There was a problem that fluctuated.

  Patent Documents 1 to 3 do not describe a crystal oscillator with a thermostatic bath using a laminated substrate provided with a copper plate at the center (core) of the substrate and provided with a prepreg made of glass epoxy and copper foil on both sides thereof. .

  The present invention has been made in view of the above circumstances, and improves the thermal conductivity of the substrate, reduces the thermal resistance between the heat source component, the crystal resonator, and the temperature sensor, stabilizes the temperature, and outputs. An object is to provide a crystal oscillator with a thermostatic bath capable of stabilizing the frequency.

  The present invention for solving the problems of the above-described conventional example is a quartz crystal oscillator with a thermostatic chamber in which a crystal resonator, a heat source component as a heat source, and a temperature sensor are mounted on a substrate. A copper plate is provided at the center of the direction, and a prepreg layer made of glass epoxy resin and a copper foil are sequentially laminated on the front and back of the main surface of the copper plate.

  The present invention is also characterized in that, in the crystal oscillator with a thermostatic bath, the thickness of the copper plate is ¼ or more and ½ or less of the thickness of the entire substrate.

  In addition, the present invention is characterized in that the thermostatic bath crystal oscillator includes an aluminum plate or a thermally conductive ceramic plate instead of the copper plate.

  According to the present invention, a quartz crystal oscillator, a heat source component that is a heat source, and a temperature sensor mounted with a crystal oscillator on a substrate, the substrate includes a copper plate at a central portion in a thickness direction, The crystal oscillator with a thermostatic bath is made of a prepreg layer made of glass epoxy resin and copper foil sequentially laminated on the front and back of the main surface of the copper plate, thus improving the thermal conductivity of the substrate and improving the heat source components, crystal resonator and temperature. This has the effect of reducing the thermal resistance between the sensor and stabilizing the temperature by stabilizing the temperature.

  In addition, according to the present invention, since the above-mentioned crystal oscillator with a thermostatic bath provided with an aluminum plate or a thermally conductive ceramic plate instead of a copper plate, a substrate with good thermal conductivity can be provided at low cost. effective.

It is sectional explanatory drawing of the board | substrate of the crystal oscillator with a thermostat which concerns on embodiment of this invention. It is an exploded explanatory view showing a mounting example of a pin type quartz crystal oscillator with a thermostat, (a) is a view seen from diagonally upward direction, (b) is a view seen from diagonally downward direction. It is an exploded explanatory view showing a mounting example of the surface mount type crystal oscillator with a thermostatic bath, (a) is a view seen from diagonally upward direction, (b) is a view seen from diagonally downward direction. It is sectional explanatory drawing of the board | substrate of the conventional crystal oscillator with a thermostat.

Embodiments of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
The crystal oscillator with a thermostatic bath according to the embodiment of the present invention is a temperature-compensated crystal oscillator in which a crystal resonator, a heat source component, and a temperature sensor are mounted on a substrate, and the substrate is at the center (core portion) of the thickness. A prepreg made of glass epoxy resin is provided on both upper and lower sides with a copper plate, and a copper foil is laminated on the outer side of the copper plate. The overall thermal resistance is reduced, especially the thermal resistance in the thickness direction of the board is greatly reduced, the temperature difference between the heat source component, the temperature sensor, and the crystal unit can be reduced, and the frequency can be stabilized. Since the thermal expansion coefficients of copper and prepreg are substantially equal, the copper plate and prepreg layer can be prevented from peeling off.

[Configuration of Substrate According to Embodiment: FIG. 1]
The structure of the substrate, which is a characteristic part of the crystal oscillator with a thermostat (the crystal oscillator with thermostat) according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional explanatory view of a substrate used in a crystal oscillator with a thermostat according to an embodiment of the present invention.
As shown in FIG. 1, the substrate (main substrate) of the quartz crystal oscillator with constant temperature bath is provided with a copper plate 10 at the central portion of the thickness of the substrate serving as a core portion, and glass epoxy resins on both upper and lower sides with the copper plate 10 interposed therebetween. Pre-pregs (prepreg layers) 11 and 12 are provided, and copper foils 13 and 14 serving as inner-layer wirings are provided on the outside thereof. That is, the prepreg and the copper foil are sequentially laminated on both main surfaces of the copper plate 10.
The central through hole is a through hole.

And the core materials 15 and 16 are laminated | stacked on the outer side of the copper foils 13 and 14, the copper foils 17 and 18 used as the wiring of an outer layer are laminated | stacked, and it becomes the structure by which the copper plating 19 and 20 was given to the outermost part. ing. Here, the copper foils 13 and 14 are inner layer copper foils, and the copper foils 17 and 18 are outer layer copper foils.
At the time of manufacturing the present substrate, the present substrate is formed by connecting the core materials 15 and 16 having copper foils formed on both surfaces thereof to the copper plate 10 of the core portion by the prepreg layers 11 and 12. The core materials 15 and 16 are formed of prepreg.
In FIG. 1, a four-layer multilayer substrate is shown, and four copper foils serving as wirings are provided. However, one copper foil may be provided on one side of the copper plate 10 to form two layers.

The thickness of the copper plate 10 can be appropriately designed so as to obtain desired characteristics, but here it is about 1/4 to 1/2 of the thickness of the entire substrate.
Further, the thickness of the prepregs 11 and 12 is set to about 1/6 to 1/7 of the copper plate 10.
The thicknesses of the core materials 15 and 16 are thicker than the prepregs 11 and 12 and are about ¼ of the copper plate 10.

That is, this substrate is formed by forming a core portion, which has been conventionally formed of glass epoxy resin, with a copper plate 10.
The thermal conductivity of copper is 400 W / m · K, which is significantly larger than the thermal conductivity of glass epoxy resin (0.3 W / m · K).
Thereby, this board | substrate can improve thermal conductivity significantly compared with the conventional board | substrate which used the glass epoxy resin as a core.

  That is, in the crystal oscillator with a thermostatic bath using this substrate, the temperature difference in the substrate surface is reduced and the heat conduction in the thickness direction of the substrate is extremely good. When mounted on another surface, the temperature difference between the front and back sides of the substrate can be reduced, and the frequency can be further stabilized.

  As a result, the quartz crystal oscillator with the thermostatic chamber efficiently conducts heat from the heat source component to the crystal unit and the temperature sensor, and reduces the temperature difference between the heat source component, the crystal unit and the temperature sensor, thereby controlling the temperature. It is possible to stabilize, prevent fluctuations in output frequency, and improve temperature-frequency characteristics.

  Further, since the thermal expansion coefficients of the laminated copper and the prepreg are close, even if there is a temperature change, the copper plate 10 and the prepregs 11 and 12 are unlikely to peel off.

Although the copper core substrate using a copper plate as a core has been described here, aluminum (thermal conductivity: 200 W / m · K) or thermal conductive ceramic (thermal conductivity: 25 W / m · K) is used instead of copper. ) Can also be used.
These have lower thermal conductivity than copper, so the effect of reducing the thermal resistance of the substrate is reduced. However, the thermal conductivity is better than that of a conventional glass epoxy resin core. is there.
Further, when aluminum or ceramic is used, the cost is reduced because it is inexpensive, and the mass productivity is excellent.

[Mounting example of a crystal oscillator with a temperature chamber]
Next, a mounting example of the thermostatic crystal oscillator will be described.
[Example of mounting a pin type crystal oscillator with a thermostat: Fig. 2]
First, a mounting example of the pin-type thermostatted crystal oscillator will be described with reference to FIG. 2A and 2B are exploded explanatory views showing a mounting example of the pin-type constant-temperature bath crystal oscillator, wherein FIG. 2A is a diagram viewed from an obliquely upward direction, and FIG. 2B is a diagram viewed from an obliquely downward direction.
As shown in FIGS. 2 (a) and 2 (b), in the pin type thermostat crystal oscillator, circuit components such as a heat source component 48 and a temperature sensor 49 are provided below the main substrate (copper core substrate) 45 described above. Installed. A substrate on which circuit components are mounted is an HIC (Hybrid IC) substrate.

  A heat radiating sheet 44 is mounted on the lower surface of the copper core substrate 45 so as to cover portions other than the circuit components, and a metal fitting 43 having the same shape is mounted below the heat radiating sheet 44. The quartz vibrator 42 is fixed by soldering. The metal fitting 43 is made of aluminum.

A copper core substrate 45 on which the heat source component 48, the temperature sensor 49, the heat radiating sheet 44, the metal fitting 43, and the surface-mounted crystal resonator 42 are mounted is fixed on the base 41 with screws 46.
Further, the cover 47 is mounted on the base 41, and the space in the base 41 including the copper core substrate 45 is sealed, thereby forming a pin type crystal oscillator with a thermostat.

[Mounting example of surface mounted crystal oscillator with constant temperature chamber: Fig. 3]
Next, a mounting example of the surface mount type crystal oscillator with a thermostatic bath will be described with reference to FIG. FIGS. 3A and 3B are exploded explanatory views showing a mounting example of the surface mount type crystal oscillator with a thermostatic bath, wherein FIG. 3A is a diagram viewed from an obliquely upward direction, and FIG. 3B is a diagram viewed from an obliquely downward direction. .
As shown in FIGS. 3 (a) and 3 (b), in the surface-mounted thermostatic chamber crystal oscillator, circuit components such as a heat source component 56 and a temperature sensor 57 are mounted on the lower surface of a substrate (copper core substrate) 54. A pin type crystal resonator 52 is soldered to the lower surface of the copper core substrate 54 and fixed thereto via a heat radiation sheet 53.

A copper core substrate 54 on which various components are mounted is fixed with a metal pin on a base 51 having a surface mounting electrode formed on the lower surface, and a cover 55 is further mounted to form a crystal oscillator with a thermostatic chamber. Is done.
2 and 3 show an example in which the heat source component, the temperature sensor, and the crystal resonator are mounted on one surface (lower surface) of the copper core substrate 44 or the copper core substrate 54. The structure mounted in the surface (upper surface) of the other side in these may be sufficient.

[Effect of the embodiment]
According to the crystal oscillator with a thermostatic bath according to the embodiment of the present invention, the copper plate 10 is used for the core, the prepregs 11 and 12 are provided on both sides of the copper plate 10, and the copper serving as the wiring outside the prepregs 11 and 12 is provided. Since the quartz oscillator with the crystal unit, the heat source component, and the temperature sensor is mounted on the substrate provided with the foils 13 and 14, the thermal conductivity of the substrate is provided by providing the core with the copper plate 10 having a high thermal conductivity. Greatly reduces the thermal resistance, reduces the temperature difference between the crystal unit, heat source component, and temperature sensor, stabilizes the temperature inside the crystal oscillator with a thermostatic chamber, and varies the output frequency. This has the effect of suppressing the temperature-frequency characteristics.

  Moreover, according to the crystal oscillator with a thermostatic bath according to the embodiment of the present invention, since the values of the thermal expansion coefficients of the copper plate 10 and the prepregs 11 and 12 are close, even if there is a temperature change, the copper plate 10 and the prepregs 11 and 12. The joint portion is difficult to peel off, and has the effect of preventing the substrate from warping.

  Moreover, according to the crystal oscillator with a thermostatic bath according to the embodiment of the present invention, when an aluminum plate or a ceramic plate is used instead of the copper plate 10, there is an effect that the cost of the substrate can be reduced.

  INDUSTRIAL APPLICABILITY The present invention is suitable for a thermostatic oven-equipped crystal oscillator that can stabilize the temperature by reducing the thermal resistance between the heat source component, the temperature sensor, and the crystal resonator, and can stabilize the output frequency.

  10 ... Copper plate, 11, 12, 33, 34 ... prepreg, 13, 14, 17, 18, 31, 32, 35, 36 ... Copper foil, 15, 16 ... Core material (prepreg) , 30 ... Core, 19, 20, 37, 38 ... Copper plating, 41, 51 ... Base, 42, 52 ... Quartz crystal, 43 ... Metal fitting, 44, 53 ... Heat dissipation sheet, 45, 54 ... PCB, 46 ... Screw, 47, 55 ... Cover, 48, 56 ... Heat source parts, 49, 57 ... Temperature sensor

Claims (3)

A crystal oscillator with a thermostatic chamber, on which a crystal resonator, a heat source component that is a heat source, and a temperature sensor are mounted on a substrate,
The substrate is provided with a copper plate at a central portion in the thickness direction, and a prepreg layer made of glass epoxy resin and a copper foil are sequentially laminated on the front and back of the main surface of the copper plate.   2. The crystal oscillator with a thermostat according to claim 1, wherein the thickness of the copper plate is ¼ or more and ½ or less of the thickness of the entire substrate.   3. The crystal oscillator with a thermostatic bath according to claim 1, wherein an aluminum plate or a thermally conductive ceramic plate is provided instead of the copper plate.

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